title: Bioengineering of dental stem cells in a PEGylated fibrin gel.
abstract: OBJECTIVE
  Postnatal stem cells can generate tooth-specific structures after transplantation in vivo, which makes them a valuable tool for dental tissue engineering. Scaffold materials that are compatible with dental stem cells, injectable and tunable for targeted regeneration are needed. A candidate material is fibrin, a biopolymer critical to hemostasis and wound healing. Rapid degradation of fibrin can be decelerated by modification with polyethylene glycol (PEG), thus creating a hybrid material for cell delivery. The aim of this study was to evaluate the suitability of PEGylated fibrin as a scaffold for dental stem cells.
  
  
  METHODS
  A PEGylated fibrin hydrogel was combined with stem cells derived from dental pulp or periodontal ligament. Cell proliferation was assessed over a 4-week period, and alkaline phosphatase activity and expression levels of mineralization-associated genes after osteogenic induction were analyzed. Cell morphology, matrix degradation, collagen production and mineral deposition were evaluated by histology. Constructs of PEGylated fibrin with dental pulp stem cells in dentin disks were transplanted in immunocompromised mice for 5 weeks and examined for new tissue formation.
  
  
  RESULTS
  All cell types proliferated in PEGylated fibrin. After osteogenic induction, alkaline phosphatase activity was higher and osteoblast-specific genes were upregulated. Dentin-specific markers increased in pulp-derived stem cells. Histologic analysis revealed degradation of fibrin, production of a collagenous matrix and mineral deposition. In vivo transplantation rendered a vascularized soft connective tissue similar to dental pulp.
  
  
  CONCLUSIONS
  Fibrin allows for the growth and differentiation of dental stem cells, can be inserted into small defects and thus appears to be a promising biomaterial for tissue regeneration in the oral cavity.
authors.affiliation: Department of Restorative Dentistry & Periodontology, University of Regensburg, Regensburg, Germany.
authors.forename: Kerstin M
authors.initials: KM
authors.lastname: Galler
authors.forename: Adriana C
authors.initials: AC
authors.lastname: Cavender
authors.forename: Umut
authors.initials: U
authors.lastname: Koeklue
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Suggs
authors.forename: Gottfried
authors.initials: G
authors.lastname: Schmalz
authors.forename: Rena N
authors.initials: RN
authors.lastname: D'Souza
mesh_terms: D000818:Animals; D057005:Bioengineering / Q000379:methods*; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D005337:Fibrin / Q000737:chemistry* / Q000494:pharmacology; D005782:Gels / Q000737:chemistry* / Q000494:pharmacology; D020869:Gene Expression Profiling; D051379:Mice; D008822:Mice, Transgenic; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000494:pharmacology; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D054457:Tissue Scaffolds / Q000737:chemistry; D014070:Tooth / Q000166:cytology* / Q000378:metabolism
chemical_list: D005782:Gels; D011092:Polyethylene Glycols; D005337:Fibrin